The present invention relates to means for updating a calendar indication of a hand type timepiece capable to indicate a calendar.
A conventional watch indicating hours often has a date indicating function as an additional function. It is the most fundamental constitution in the ordinary watch to conjoin a gear train for driving the hand which indicates the hours, so as to drive the date indicator caused by a gear operating one round in each 24 hours. However, in such a driving mechanism, as the date indicator is driven in complete synchronization with the gear train of a hour system, the present form of the time indicator indicates a nonexistent date such as the 31st day in a shorter month having loss, than 31 days. As a result, a user must manually modify the date indicator by quick-feed method in each time mentioned above so as: to set to correct date.
It have been variously proposed, for instance in a timepiece system constituted as block diagrams shown in FIG. 10, to automatically remove the non-existent date of the end of the month so as to more consistently indicate the correct date. In FIG. 10, the numeral 101 indicates an oscillating circuit which produces a reference signal, the numeral 102 indicates a frequency dividing circuit, the numeral 103 is a driving circuit A, the numeral 104 is a driving circuit B, the numeral 105 is a motor A for driving the hands, the numeral 106 is a motor B, the numeral 107 is a hands driving gear train, the numeral 108 is a date indicator driving gear train, the numeral 109 is a 24 hours switch, the numeral 110 is a hand, and the numeral 112 is a calendar control circuit.
In ordinary time indication, the reference signal OSC produced by the oscillating circuit 101 is divided into a desired frequency dividing signal by the frequency dividing circuit 102 so as to produce, by the driving circuit A, a driving signal DRV1 required to drive the motor A. The hand is driven by the driving signal DRV1 so that ordinary time indication is carried out.
Furthermore, in addition to the motor and the gear train for driving the hand, the driving circuit B, the motor 106 and the gear train 108 for driving the date indicator 111 are provided to control a driving operation of the date indicator 111, independent of the drive operation of the hand. The driving operation of the date indicator is performed on the basis of a signal 24SW from the 24 hour switch.
An example of the 24 hour switch 109 comprises, as shown in FIG. 11, a 24 hour wheel 201 and a contact 202, the 24 hour wheel 201 circuits once every 24 hour and is connected to a Vdd potential which is in the state of a high (hereinafter referred to as "H") level. When the 24 hour wheel 201 is conjointly rotated with the hand driving gear train and close the contact 202, the potential of the contact 202 forms the "H" level and is output as the signal 24SW.
Moreover, in FIG. 10, the 24 hour switch 109 is conjoined to the hand driving gear train and outputs the signal 24SW as an ON signal every 24 hour. On receiving the signal 24SW, the driving circuit B 104 outputs the driving signal DRV2 required to advance the date indicator one day, to the motor B. As a result, the date indicator is advanced by one day during each 24 hour period.
The calendar control circuit 112 contains data on the current day, month, and year. The date advances by one day by the signal 24SW, but the calendar control circuit 112 outputs the non-existent date removing signal DD when the day, month, and year data indicate that the displayed date is non-existent. Upon receiving a signal DD, the driving circuit B106 outputs a driving signal DRV2 required to drive the date indicator by one day.
The non-existent date removing operation of the date indicator is continued until the non-existent state of the date indicator is removed. For instance, in the case of February of a leap year, the date is advanced by two days as soon as the 30th day is indicated. Furthermore, in the case of February of other than a leap year, the date is advanced by three days as soon as the 29th day is indicated. As a result, the date indicator always indicates the correct date.
Since the removing operation of the non-existent date is also automatically carried out in shorter months, a user need not modify the date as conventionally required. On the other hand, according to the conventional example described in the present invention, because the 24 hour switch 109 is conjointly driven to the hand driving gear train, an ON-signal 24SW from the 24 hour switch 109 is output during the time modifying operation of the usual analog timepiece.
In view of the ordinary time modification, the time lag need be corrected less frequently because the accuracy of electronic timepieces has improved. However, it remains necessary to modify the time lag during an overseas trip, or in countries introduced with summer time system.
Essentially, since the user dose not need to modify the date after modifying the time, it is more convenient, that the date indicator be conjointly operated when a user advances or returns the time indicator.
In a typical conventional structure, although the 24 hour switch 109 is turned on in ganged operation with the hand driving gear train 107, each signal 24 SW to be outputted becomes the sane signal in a contact construction shown in FIG. 11, regardless whether the rotative direction of the 24 hour wheel 201 is in the normal or reverse direction in the drawing.
Therefore, in a conventional control wherein the 24 hour switch is turned on in either rotating direction, time modification is carried out by rotating the hand in the reverse (counterclockwise) direction, that is, the time is modified to a returning direction, and the date indicator advances by one day when the 24 hours switch 109 is turned on. Thus, the date indicator lags behind the calendar date.